1. Field of the Invention
The present invention relates to the structure of a battery that permits the battery to be stored indefinitely and thereafter to be activated by rotating a first part of the battery with respect to a second part of the battery. The outside dimensions of the battery are the same before and after activation.
2. The Prior Art
A search of the prior art has found that a number of different structures have been employed for initiating activation of a deferred action battery. Some of these structures will be briefly discussed in the following paragraphs.
It will be seen that none of the known structures resembles the present invention, which is believed to be new in the art. This brief survey of the prior art will, however, serve to provide an understanding of the types of problems inherent in the structures of prior art batteries, and this understanding will then permit a better appreciation of the advantages of the structure used in present invention.
In U.S. Pat. No. 2,832,814 issued Apr. 29, 1958 to Shannon, there is disclosed a stem that extends from the battery under a protective cap and that allows the user to break a frangible weakened portion of the electrolyte reservoir to activate the battery.
In U.S. Pat. No. 3,228,801 issued Jan. 11, 1966 to Snyder, there is disclosed a deferred action battery in which an impervious barrier is located between the electrolyte paste and the zinc can. To activate the battery, the impervious barrier is drawn out of the battery thereby permitting contact of the previously separated elements.
In another type of deferred action battery, a liquid electrolyte is stored within the zinc cup, and the remaining elements of the battery are plunged into the liquid electrolyte to activate the battery. This type of structure is shown in U.S. Pat. No. Re. 15,846, issued May 27, 1924 to French and in U.S. Pat. No. 1,518,301 issued Dec. 9, 1924 to Benner, et al.
In the patent of French, the cartridge is provided with external threads that engage internal threads located at the open upper end of the zinc can. The user twists the cartridge relative to the zinc can, and the threads cause the cartridge to be screwed into the can. As the cartridge advances into the can, it strikes and breaks a wax seal that confines the liquid electrolyte, permitting the latter to contact the cartridge, thereby activating the battery.
This activation structure suffers from two major drawbacks. First, the wax seal may be broken accidentally; and second, the length of the battery after activation is shorter than its length before activation. As will be seen below, the structure of the present invention overcomes both of these disadvantages.
Probably the most widely used structure for activating a deferred action battery is the frangible member. Frangible members have been employed in U.S. Pat. No. 1,417,692 issued May 30, 1922 to Rosen; U.S. Pat. No. 1,503,380 issued July 29, 1924 to Rosen, et al.; U.S. Pat. No. 2,852,292 issued Sept. 16, 1958 to Salauze; U.S. Pat. No. 3,376,166 issued Apr. 2, 1968 to Hruden; and, U.S. Pat. No. 4,031,296 issued June 21, 1977 to Sarbacher, et al.
One problem common to batteries employing a frangible member is that the member is susceptible to being broken through inadvertence, as when the battery is accidentally dropped. A frangible member is by its very nature more readily broken than the remaining structure. In some designs the frangible member is also susceptible to damage at temperature extremes. As will be seen below, the battery of the present invention overcomes these problems of earlier designs.